1. Field of the Invention
The present invention relates to a positioning device for a hand-held setting tool having an actuation switch for actuating the setting tool, with the positioning device including a rod-shaped holder defining a longitudinal axis, connection means for the setting tool arranged at an end of the holder, actuating switching means for actuating the actuation switch of the setting tool and including an actuation element, a switching link that connects the actuation element with the actuation switch of the setting tool, and a safety device for preventing actuation of the actuation switch of the setting tool at a predetermined orientation of the setting tool.
2. Description of the Prior Art
Positioning devices of the type described above are used, e.g., at overhead works with hand-held setting tools in case of high ceilings when working is possible only using working platforms or ladders. Setting tools, which can be used with such devices, can be driven with solid, gaseous, or liquid fuels or with compressed air or electricity.
U.S. Pat. No. 4,479,599 discloses a positioning and actuation device for a combustion-operated setting tool and including connection means for the setting tool, which is arranged at an end of an elongated holder and is formed as a rod or a bar. The rod or bar is axially displaceable relative to the connection means for actuating the actuation switch of the setting tool secured on the connection means via coupling means. For actuating the setting tool, the tool should be placed with its muzzle part against a ceiling and then be displaced in the direction of the ceiling with the holder or rod by the user.
Further, the positioning and actuation device has a safety device which prevents the setting tool from being actuated when the muzzle part is oriented exactly in direction of the force of gravity. For this purpose, the safety device has a ball which is guided in a channel extending in the connection means diagonally to the longitudinal axis of the rod and which rolls into the movement link of the rod when oriented in direction of the force of gravity, and prevents a further movement of the rod relative to the connection means and, therefore, prevents actuation of the setting tool secured on the connection means.
The drawback here consists in that the actuation of the setting tool can only be safely prevented when the positioning and actuation device with the setting tool is oriented exactly with the muzzle part facing in direction of the force of gravity.
U.S. Pat. No. 7,014,085 discloses an explosion-actuated setting tool having a housing, an elongated holder projecting therefrom, and a ball-controlled safety locking device which permits the setting tool to be actuated only in a vertical or almost vertical orientation opposite the force of gravity. The ball of the ball-controlled device is arranged in an annular receiving space between the holder and the housing.
However, the drawback of this setting tool consists in that high forces are applied when pressing on the parts which is required for the blocking function in the blocking position, and these forces can lead to wear over the course of time and can reduce the effectiveness of the safety locking device.